JP3224183B2 - High molecular weight polycarbonate with excellent heat stability - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polycarbonate having excellent heat stability, and more particularly to a polycarbonate produced by a melt transesterification method, which is free from coloring due to thermal deterioration and has a low phenolic hydroxyl group content.

[0002]

BACKGROUND OF THE INVENTION High molecular weight polycarbonates are general purpose engineering thermoplastics that have a wide range of uses, especially for injection molding or as glass sheets in place of window glass.

[0003] Polycarbonate is an interfacial polycondensation method (phosgene method) in which methylene chloride is added as a solvent to an aqueous solution or suspension of a sodium salt of dihydric phenol, and phosgene is blown in to react the dihydric phenol with diphenyl carbonate. It is manufactured by a transesterification method in which carbonic diester is melted by heating and polycondensed by transesterification under high temperature and reduced pressure.

[0004] Among these polycarbonate production methods, the interfacial polycondensation method is generally widely used. However, this method not only requires the use of extremely toxic phosgene, but also leaves chloride ions in the produced polycarbonate. When chlorine ions remain in the polycarbonate, the polymer is colored by molding at a high temperature. Therefore, it is necessary to wash the obtained polymer in order to reduce the concentration of residual chloride ions. Furthermore, in this washing step, a high concentration of methylene chloride used as a solvent in the wastewater has recently become a major environmental problem.

[0005] On the other hand, the transesterification method has the advantages that no highly toxic phosgene or methylene chloride, which is environmentally problematic, is not required, and that a step of removing residual chloride ions is not required. It is desired to establish an industrial production technology of polycarbonate by the method. However, polycarbonate produced by the transesterification method generally suffers more severe coloring and lowering of the molecular weight at the time of molding processing than polycarbonate produced by the phosgene method.

In the transesterification method, generally, the reaction is carried out at a high temperature and a high pressure in the presence of a catalyst, and the obtained polymer is pelletized and taken out without a washing step. Therefore, the polymer contains not only a catalyst and unreacted raw materials but also compounds having various structures due to side reactions. These have been pointed out as causes of the low thermal stability of the polycarbonate obtained by the transesterification method, but the details of the causal relationship have not been elucidated, and effective measures have not been taken.

As described above, the production of polycarbonate by the transesterification method is an excellent method in terms of safety and environment, but has a problem in the stability of the obtained polycarbonate. To solve these problems, a number of compounds have been proposed to be effective as stabilizers. For example, JP-A-4-175368 proposes adding an acidic compound such as a sulfonic acid or a phosphorous acid to a polycarbonate obtained by a transesterification method. However, the coloring in the air at 160 ° C. was somewhat improved as compared with the conventional transesterification polycarbonate, but was not satisfactory as compared with the polycarbonate produced by the phosgene method.

Accordingly, an object of the present invention is to provide a polycarbonate which is free from coloring at the time of molding by the melt transesterification method and has excellent heat stability without coloring due to exposure to heat for a long time. It is in.

[0009]

Means for Solving the Problems The present inventors have synthesized polycarbonates (hereinafter referred to as transesterification polycarbonates) produced by a melt transesterification method under various conditions to achieve the above object, The relationship between the coloring during molding and the coloring by a heating test at 160 ° C. in air was examined in detail. As a result, it was found that the type and concentration of the catalyst used for the polymerization were not directly related to the coloring by heating in the air, and the oxidation of the phenolic hydroxyl group was the main cause of the coloring. As the phenolic hydroxyl group, monovalent phenol which is a leaving component,
Includes unreacted dihydric phenols and phenolic hydroxyl terminal at polymer terminals. Further, as described above, transesterification polycarbonate contains side reaction products having various structures, and many of them have phenolic hydroxyl groups, which also cause coloring in the air. . In addition, the molecular weight of polycarbonate decreases during molding and during a heating test at 160 ° C in air.Through detailed studies, it has been clarified that the cause is mainly a hydrolysis reaction, and the phenol generated due to this molecular weight reduction. It has been found that the terminal of a hydroxyl group also causes coloring.

Based on these findings, a detailed study of the polymerization formulation reduces the concentration of monohydric phenol and unreacted dihydric phenol, which are eliminated components, suppresses side reactions, and suppresses most of the polymer terminals. Succeeded in synthesizing a polycarbonate having a phenyl carbonate terminal. Furthermore, the addition of a compound containing boron succeeded in suppressing the generation of phenolic hydroxyl group terminals due to the hydrolysis reaction, and completed the present invention.

That is, the present invention relates to a polycarbonate produced by a melt transesterification method from a dihydric phenol and a carbonic acid diester , wherein the amount of the phenolic hydroxyl group terminal contained in the polycarbonate is 3.0 × 10 ⁻⁵ mol / g
The monovalent contained in the polycarbonate is as follows:
The amount of phenol is 1.2 × 10 ⁻⁶ mol / g or less,
The amount of the dihydric phenol contained in the polycarbonate is
The present invention relates to a polycarbonate characterized by being 2.0 × 10 ⁻⁷ mol / g or less .

According to the present invention, by satisfying the above conditions, it is possible to obtain a polycarbonate having excellent heat stability, which is substantially free from coloring during molding and coloring due to exposure to heat for a long time.

In the present invention, the amount of the monohydric phenol contained in the polycarbonate produced from the dihydric phenol and the carbonic acid diester by the melt transesterification method is 1.2 × 10 ⁻⁶ mol / g or less . Monohydric phenols include those formed by side reactions, but most of the elimination components.

The amount of the dihydric phenol contained in the polycarbonate produced from the dihydric phenol and the carbonic acid diester by the melt transesterification method is 2.0 × 10 ⁻⁷ mol / g.
It is as follows . Dihydric phenols include those produced by side reactions, but most of the unreacted ones.

If the amount of the phenolic hydroxyl group terminal contained in the polycarbonate exceeds 3.0 × 10 ⁻⁵ mol / g, coloring by heat becomes severe. The amount of monohydric phenol, which is a desorbing component, contained in polycarbonate is 1.2 × 10 ^-6 mol / g
If it exceeds, coloring by heat and molecular weight reduction become severe.
If the amount of unreacted dihydric phenol contained in the polycarbonate exceeds 2.0 × 10 ^-7 mol / g, coloring and reduction in molecular weight due to heat become severe, and side reactions via the formation of isopropenylphenol and the like occur. Is more likely to occur,
Physical property value decreases.

As the dihydric phenol constituting the polycarbonate of the present invention, bisphenol A (2,2-bis (4-hydroxyphenyl) propane) is typical, and in addition, for example, bis (4-hydroxyphenyl) ) Methane, 1,1-bis (4-hydroxyphenyl) ethane,
2,2-bis (4-hydroxyphenyl) butane, 2,2-
Bis (4-hydroxyphenyl) -4-methylpentane, 2,2-bis (4-hydroxyphenyl) octane,
Bis (4-hydroxyphenyl) phenylmethane, 4,4 '
-Dihydroxy-2,2,2-triphenylethane, 2,2-
Bis (3-bromo-4-hydroxyphenyl) propane, 2,2-bis (3,5-dibromo-4-hydroxyphenyl) propane, 1,1-bis (4-hydroxy-3-methylphenyl) propane, 2 2,2-bis (4-hydroxy-3-isopropylphenyl) propane, 2,2-bis (4-hydroxy-3-sec-butylphenyl) propane, 2,2-bis (3,5-dimethyl-4-hydroxy Phenyl) propane, 1,1-bis (4-hydroxy-3-te
bis (hydroxyaryl) alkanes such as rt-butylphenyl) propane, 1,1-bis (4-hydroxyphenyl) -p-diisopropylbenzene, 1,1-bis (4-hydroxyphenyl) -p-diethylbenzene,
Bis (hydroxyaryl) arenes such as 1,1-bis (4-hydroxyphenyl) -m-diisopropylbenzene, 1,1-bis (4-hydroxyphenyl) cyclopentane, 1,1-bis (4-hydroxyphenyl) ) Cyclohexane, bis (hydroxyaryl) cycloalkanes such as 1,1-bis (4-hydroxyphenyl) cyclooctane, 4,4′-dihydroxydiphenyl ether,
Dihydroxydiaryl ethers such as 4,4'-dihydroxy-3,3'-dimethyldiphenyl ether; dihydroxydiaryl sulfides such as 4,4'-dihydroxydiphenyl sulfide and 4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfide , 4,4'-dihydroxydiphenylsulfoxide, 4,4'-dihydroxy-3,3'-dimethyldiphenylsulfoxide, dihydroxydiarylsulfoxides, 4,4'-dihydroxydiphenylsulfone, 4,4'-dihydroxy- And dihydroxydiarylsulfones such as 3,3′-dimethyldiphenylsulfone. These dihydric phenols may be used alone or
It may be contained in a form mixed with more than one kind.

Examples of the carbonic acid diester used in producing the polycarbonate of the present invention include diphenyl carbonate, ditolyl carbonate, bis (chlorophenyl) carbonate, m-cresyl carbonate, dinaphthyl carbonate, dicyclohexyl carbonate, dimethyl carbonate, and the like. Examples include diethyl carbonate and dibutyl carbonate. Among these carbonic acid diesters, diphenyl carbonate is frequently used.
These carbonic diesters can be used alone or in combination of two or more.

As described above, the coloring by heating in the air, such as coloring during molding, does not directly affect the type or concentration of the catalyst used during polymerization. Therefore, the catalyst used for producing the polycarbonate of the present invention is not particularly limited. However, in consideration of the generation of a compound having a phenolic hydroxyl group due to a side reaction during polymerization and the likelihood of a hydrolysis reaction generating coloring and generating a phenolic hydroxyl terminal, a nitrogen-containing basic compound, a compound containing a Li atom and a Sb It is preferable to use at least one selected from compounds containing atoms as a catalyst.

Examples of the nitrogen-containing basic compound include pyridine, 4-aminopyridine, 2-aminopyridine, N,
N-dimethyl-4-aminopyridine, N, N-diethyl-
4-aminopyridine, 4-pyrrolidinopyridine, 2-hydroxypyridine, 4-hydroxypyridine, 2-methoxypyridine, 4-methoxypyridine, picoline, pyrimidine, imidazole, 2-methylimidazole, 4-
Methylimidazole, 2-dimethylaminoimidazole, 2-methoxyimidazole, 2-mercaptoimidazole, pyrazoleaminoquinoline, benzimidazoli, N, N-dimethylaniline, pyrrolidine, morpholine, N-methylmorpholine, piperidine, piperazine,
1,8-diazabicyclo [5,4,0] -7-undecene (DBU)
, 1,5-Diazabicyclo [4,3,0] -5-nonene (DBN)
And the like. These nitrogen-containing basic compounds can be used alone or in combination of two or more.

Examples of the compound containing a Li atom include lithium hydroxide, lithium acetate, lithium hydrogen carbonate, lithium carbonate, lithium stearate, lithium borate, lithium borohydride, lithium benzoate and the like.

Examples of the compound containing an Sb atom include antimony acetate, antimony oxalate, triphenylantimony, antimony trioxide, antimony pentoxide, triphenoxyantimony, trimethoxyantimony, triethoxyantimony, and antimony trichloride. Can be

The amount of the catalyst used may be within a range that does not impair the polycondensation reaction. For example, 10 ^-8 to 10 ^-2 mol, preferably 10 ^-7 to 10 ^-3 , per mol of the dihydric phenol is used. It is about a mole. If the amount of the catalyst used is less than 10 ^-8 mol, it is necessary to react for a long time at a high temperature of 220 ° C to 300 ° C in order to obtain a desired degree of polymerization, for example, a molecular weight of about 5,000 to 50,000. It is not effective as a typical manufacturing method. Further, if it exceeds 10 ^-2 mol, the coloring due to side reactions during polymerization becomes not negligible, and the amount of catalyst remaining in the produced polycarbonate increases,
The molecular weight is easily reduced by the hydrolysis reaction.

In the present invention, it is preferable to further use a compound containing a boron atom. Examples of the compound containing a boron atom include boric acid or borate ester. These may be added at any time before, during or after the polymerization.

Examples of the borate ester include, but are not limited to, trimethyl borate, triethyl borate, tributyl borate, triphenyl borate, tolyl borate, and trinaphthyl borate. These borate esters can be used alone or as a mixture of two or more kinds, and can also be used by mixing boric acid and borate esters.

The amount of the compound containing a boron atom may be within a range that does not deteriorate the physical properties of the polycarbonate to be produced, and is, for example, about 0.01 to 500 mol, preferably about 0.1 to 200 mol, per 1 mol of the catalyst used. . When the amount is less than 0.01 mol, the effect of heat stabilization on the polycarbonate is small, and the reduction of the molecular weight and the coloring at the time of molding are not negligible.

[0026]

EXAMPLES The present invention will be described below in more detail with reference to Examples, but the present invention is not limited to these Examples.

Examples 1 to 6 A polycarbonate was produced from diphenyl carbonate (DPC) and bisphenol A (BPA) by a transesterification method. In the production, as shown in Table 1, the type and concentration of catalyst (molar ratio to BPA) and the type and concentration of compound containing boron atom (molar ratio to catalyst) were changed, and diphenyl carbonate and bisphenol A suitable for each were changed. By controlling the polymerization reaction in detail by selecting the charged molar ratio of the above, six types of polycarbonates having a low phenolic hydroxyl group concentration shown in Table 2 were obtained. The inherent viscosity ([η]), weight average molecular weight (Mw), phenol concentration ([PhOH]), bisphenol A concentration ([BPA]),
Table 2 shows the phenolic hydroxyl group terminal concentration ([OH]) and the hue (YI). The intrinsic viscosity ([η], dL / g) was measured in methylene chloride at 20 ° C. using an Ubbelohde viscometer. The weight average molecular weight (Mw) was determined by a light scattering method or a GPC method using a universal calibration curve.
The effect of the difference of the measurement methods was within the experimental error. Phenol concentration ([PhOH], mol / g) and bisphenol A concentration ([BPA], mol / g) were determined by an absolute calibration curve method using a liquid chromatograph or a gas chromatograph. The effect of the difference of the measurement methods was within the experimental error. The phenolic hydroxyl terminal concentration ([OH], mol / g) was determined by the method of Horbach et al. (Markromol, Chem., 88, 215 (1965)) and the method of Pryde et al. (J. Appl. Polym. Sci., 25, 2537 (1980)). Hue (YI) was measured using a 2 mm-thick sheet prepared by a hot press quenching method using Nippon Denshoku Industries Co., Ltd.
It was measured by DJ-1001DP. These polycarbonates were left in an oven at 160 ° C. in the air, and the weight average molecular weight and YI value after 30 days were measured. Table 2 shows the results.

Comparative Examples 1-4 As in the examples, various polycarbonates were prepared from diphenyl carbonate and bisphenol A by a transesterification method. In the production, four kinds of polycarbonates having a high phenolic hydroxyl group concentration shown in Table 2 were obtained mainly by adjusting the charged molar ratio of diphenyl carbonate and bisphenol A as shown in Table 1. Table 2 shows the intrinsic viscosity, weight average molecular weight, phenol concentration, bisphenol A concentration, phenolic hydroxyl terminal concentration and hue (YI) of the obtained polycarbonate. These polycarbonates were left in an oven at 160 ° C. in the air, and the weight average molecular weight and YI value after 30 days were measured. Table 2 shows the results.

As is evident from Table 2, the polycarbonates shown in the comparative examples show a marked decrease in molecular weight and coloration after being left in the air at 160 ° C. for 30 days, while the polycarbonates shown in the examples show It can be seen that there is almost no decrease in the molecular weight and no coloring, and the heat stability is excellent.

[0030]

[Table 1]

[0031]

[Table 2]

Claims (8)

(57) [Claims] 1. A polycarbonate produced by a melt transesterification method from a dihydric phenol and a carbonic acid diester , wherein the amount of phenolic hydroxyl group terminals contained in the polycarbonate is 3.0 × 10 ⁻⁵ mol / g or less . ,
Amount of monohydric phenol contained in the polycarbonate
Is less than 1.2 × 10 ^-6 mol / g,
The amount of dihydric phenol contained in the solution is 2.0 × 10 ^-7 mol /
g polycarbonate. 2. A method comprising the steps of dihydric phenol and carbonic acid diester
Polycarbonate manufactured by melt transesterification
Diester carbonate per mole of dihydric phenol
Manufactured using 1.035 to 1.050 moles of
Phenolic hydroxyl group contained in the polycarbonate
The amount of the edge is 3.0 × 10 ⁻⁵ mol / g or less, and the polycarbonate
The amount of monohydric phenol contained in the Bonate is 1.2 × 10
^-6 mol / g or less, contained in the polycarbonate
Is less than 2.0 × 10 ^-7 mol / g
A polycarbonate characterized by the above. 3. A method comprising dihydric phenol and carbonic acid diester
Molten esters in the presence of catalysts and compounds containing boron atoms
A polycarbonate produced by an exchange method,
1.03 of carbonic acid diester to 1 mole of polyhydric phenol
5 to 1.050 moles per mole of dihydric phenol
And the catalyst is used in an amount of 10 ^-8 to 10 ^-2 mol,
Of the compound containing a boron atom in an amount of 0.01 to 500 moles
Manufactured in the above-mentioned manner and contained in the polycarbonate.
When the amount of the enol hydroxyl terminal is 3.0 × 10 ^-5 mol / g or less,
And the monovalent phenol contained in the polycarbonate
Is less than 1.2 × 10 ^-6 mol / g,
The amount of dihydric phenol contained in the carbonate is 2.0 × 10
Polycarbonate characterized by being ^-7 mol / g or less
G. 4. The method of claim 1, 2 monohydric phenols included in the polycarbonate is a monovalent phenol desorption component
Or the polycarbonate according to 3 . 5. The method according to claim 1, wherein the dihydric phenol contained in the polycarbonate is unreacted dihydric phenol .
The polycarbonate according to any one of the preceding claims. 6. A process for producing a polycarbonate from a dihydric phenol and a carbonic acid diester by a transesterification method, wherein the catalyst is one selected from a nitrogen-containing basic compound, a compound containing an Li atom and a compound containing an Sb atom. The polycarbonate according to any one of claims 1 to 5 , wherein the above is used. 7. A catalyst is used per mole of dihydric phenol.
The polycarbonate according to claim 6 , wherein the polycarbonate is used in an amount of 10 ^-8 to 10 ^-2 mol. 8. When a polycarbonate is produced from a dihydric phenol and a carbonic acid diester by a melt transesterification method, one type selected from a nitrogen-containing basic compound, a compound containing an Li atom and a compound containing an Sb atom as a catalyst. Using the above, a compound containing a boron atom was added in an amount of 0.
The polycarbonate according to any one of claims 1 to 7 , wherein the polycarbonate is used in an amount of from 01 to 500 mol.